My newish ultra has a problem accessing a few shows on different streaming services. When I try to watch, I get the spinning circle, then a message that says “Check Device Power,” with directions to check connections, but our connections are fine. Just with one show on Prime and one on Hulu.
Have you tried rebooting your wireless network to see if that helps resolve the issue you are experiencing? In addition, try removing the channel from the Roku home screen by navigating to the channel tile, pressing the * key on your remote and choosing 'Remove channel'. Then restart your device from Settings>System>System restart. Once your player starts up again, add the channel back once more.
Does this clear up the issue you are seeing? Please keep us posted what you find out.